Read about the issues the earlier ones had, so a little concerned about it. Should be ok though.

My real question though is if anyone has ever heard about someone converting one of these to 10mm. I'm assuming a 40S&W barrel could be rebored, and then maybe a heavier buffer for it. What else would be involved?

Have a 9mm jrc that I've only recently shot for the first time. As a range toy I'm very happy with it and its gone bang every time.

JRC has an FAQ on their website that speaks specifically about the blowback limitations with regards to 10mm and why it doesn't work in their design.

First: Early JRC's had the normal teething problems many firearms, especially blow-back semi-autos always seem to have. Lots of reasons for that and I have written about that before, as has others. Anyway, I have a "new" JRC...bought last year, and it had been one of the most dependable semi-auto rifles I have owned. Amazing how it can use even cheap Korean magazines and shoots all my home reloads without an issue. Very accurate to boot, much more so than any 9mm AR I have owned. Love this rifle.  JRC has ironed out any details and have a good knowledge base to work from now.

As for the .45 model, those problems are past. They figured out the root causes and addressed them. Do read their information about the magazines however.

Now,  the 10mm. There is are good reasons the .40 caliber S&W became popular. As has been stated, the 10mm is a hotter load than the .40 and its use in blow-back firearm is problematic. I fully agree that the 10mm would make a better round for a carbine used for defense from either man or beast, but the physics of the round and the firearm its expected to operate in dictate what is possible here. Of course there have been some 10mm conversions done. Poke around and you can read about them. I have even seen a Hi-Point 995 converted to 10mm.

I picked up a .45 JRC a year ago and I've been very impressed with the accuracy, especially with 185 gr bullets. Only issue I had was with feeding from unmodded mags, once I bent the spring no issues. My JRC factory mag had a heavier spring than the Glock G21 mags I bought but after the mod they all work fine.  
Other than the MecTech conversions I don't know of any factory production 10mm carbines. Theuron Defense advertises a 10mm rifle but have yet to see one (list price is $1000). I've got an old beater Colt 1911 that's in need of a new barrel and I've been thinking about trying a MecTech 10mm 1911 upper but I'm not sure if the .45 and 10mm 1911s have the same size magwell.

Edit: Just checked the MecTech site, they say the standard 1911 frame takes both .45 and 10mm mags, so this would work. Stripped Mectechs start around $360 plus another $100 for an M4 stock. Or I could sell my Colt for 5 bills and add it to the above amount and there's a Theuron. I haven't read much about the Theuron Defense carbines but what little I've seen is good. If they're as good or better than the JRC that's not a bad deal.

Anyone here suppress one of these? I just ordered an Octane 45

I threw my octane 45 on my 9mm JRC and gave it a few mag dumps. The gun functioned just fine. I wasn't shooting my subsonic loads so the sound was hard to judge due to the loud sonic cracks. My impression was once im moving subsonics through the barrel the gun will sound very sweet suppressed as I didn't detect a ton of noise escaping from the chamber.

I am curious as to what is range "toy" about the JRC ?

For me, there are some design related things that make me question how it will stand up to long term wear and tear. The screws you have to remove for disassembly and the bolt handle wearing against the receiver being the top two. I've put about 500 rounds through my 9mm and the bolt handle has worn off the finish on the receiver where its making contact as it slides back and forth.

There was a review done on youtube that I saw which covers these in pretty good detail, let me see if I can dig it up...

Edit-
Here it is
https://www.youtube.com/watch?v=WFugeV5pnfo

skip to 14:50 to get to the good stuff. Its a lengthy review but he hits on a few valid observations. I've also experienced the light primer strike issue on occasion when doing very rapid fire as well which he mentions.

I have seen that YouTube video review, watched it a few times. The guy gets pretty picky about some things that he "Thinks will go wrong". There is a big difference between what some YouTube poster thinks and what will really happen. Some of the things he mentions are just "out there" and are a whole lot of speculation on his part. I don't know what makes him into an expert.

As for finish wear, big deal. There is a big difference from wearing off some of the black and wearing out the metal in the receiver.  The finish on any firearm, such as the slide on my pistols, will quickly wear at certain contact points. This has not caused any problems to those hand guns however.

As for the screw on the charging handle, I think a few people make too a big deal out of that. In a normal cleaning there really isn't any good reason to remove the bolt. You can easily clean the internals by just locking the bolt back. Even on a lowly pot metal High Point 995 (which is a lot of trouble to take down) they will tell you not to worry about doing a complete strip until around 1,000 rounds. You will see Hi-Po's with thousands of rounds through them and they are friggin' zink pot metal!  So, I have no concerns with the JRC.  After all, what is an AR receiver made of? And for cleaning, I continually read of people bragging about how many thousands of rounds they will put through some firearms with minimal cleaning.

I think sometimes we worry too much about things that will likely never happen.( There is an old saying that 90% of the things you worry about will never happen anyway). And, we have too many "internet experts" spouting off their person theories about how the world should be. All too often their personal biases get in the way of frank and objective reviews. But, its your money, go with what you want and trust.

Unless you have an affinity for JRC, this link might help

 

Definitely see both sides of the thought process. For me its enough little things that I would grab several other weapons before grabbing the JRC if my life depended on it. However for fun at the range its awesome... hence why it falls into range toy category in my mind.

In other news I just got my approved SBR form 1 for my JRC today... so i'm looking forward to a more compact package! Got the 45 conversion kit as well so gonna have chopped down 9 and 45 barrels on hand.

Actually if my life depended on it.....I would trust my JRC over a 9mm AR. Had two of them, both decent guns but this JRC shoots rings around them and is 100% reliable. But, that is just my experience (and others)  but........YMMV

You have other options. The Oly 10mm certainly is one of them.

Oh yeah for sure, my JRC has been much much more reliable than plenty of 9mm AR options out there. I also give JRC huge credit for their awesome customer support and putting something new out into the market. And I love love love the multi-caliber option and that they take glock mags. These were huge selling points for me personally. No regrets here with my purchase, I just can't say to myself that its absolutely perfect. But I'm also the first to admit that I'm OCD about many things, a perfectionist, etc...

Would buy mine again in a heart beat.

Even more thrilled now that my JRC is about to become an SBR once I get it engraved and the barrel cut down!

An honest, clear post. You are correct, we can find short comings in most everything. Any machine is a compromise as the builder has to consider cost and manufacturing ability, limits on material, whatever. After all, if you made a "perfect" firearm but it cost $5,000 who could afford it? Many things in life are compromises so we just have to make our choices based on what factors are most important to us personally. I find the JRC to be a great value for what it cost and to be totally reliable in my usage. I too have zero regrets with this firearm and would buy another in a heart beat.

I had and early model in 45 ACP and it was a challenge to get running reliably.  But I live only 25 miles from where they are built and they were great to deal with.  They got it running great.  After I got 500 rounds through it without a hitch, NY went and illegally passed the SAFE act.  So it now resides safely out of state where I hope to reside soon too.

NY...we are so sorry for you....please come and live in a Free State like Kentucky!

If I didn't live in Texas, I think I would love to live in Kentucky. All that bourbon!

Can anyone tell me the specific problem the .45 JRC's are having with feeding.  Mine is doing the same thing
and I'm getting ready to ship it back to them for repair.  It's funny it will fire a whole factory mag and on the
next one it will have feeding problems.  

I wish it would also feed extended mags.

Have you visited their web page and watched the videos on this? They have some information out on some issues with certain Glock magazines and how the spring fits in them. There are tips on how to easily correct this. Also, is your .45 an "early" or "late" model? I know on the 9mm models they added a magazine stop and changed the feed ramp some time back making the later models more reliable. The earlier models are easily upgraded to the newer specs.

It is a timing issue.  The carbine can cycle faster than the Glock mag can feed it.  In fact, I was at the factory once and they showed me 6 different springs that came in factory mags.  On mine, it would always jam on the 8th round.  The fix on the website will show you how to modify the spring to aid feeding.  On mine, I finally slowed it down enough by using a rifle length recoil spring and an eleven ounce rifle buffer from Heavy Buffer.  

This issue was pretty much limited to the 45 ACP carbines.  The 9mm and 40 S&W versions have very good reliability records.  Still in NY as kids settle in around the country and elderly in-laws keep on kicking.  Looking into Idaho Falls.  None too shabby living on the west side of he Grand Tetons and near Yellowstone.  

I purchased a 'post-modified' JRC .45 late last year, my only issue was with unmodified Glock mags and the factory Glock mag I received with mine was NOT modded. It only involves removing the spring from the mag and bending the very last loop up to put more pressure on the back of the follower. The loops in the spring will sit at a similar angle to the follower, you want that last loop bent up about 90 degrees from the rest of the loops ( I think JRC had some good pics on their website of this). My Glock mag that came with the rifle also seemed to have a heavier spring than the other factory Glock mags I purchased but all have functioned %100 AFTER I bent the spring.

Quiter........  Im waiting on my approval, but I saw no reason not to SBR it.

JR Carbine also makes a .45 that takes 1911 mags.That's the one I'd want.

That's actually the one I was looking for when I bought mine, but I couldn't find one anywhere. There's a JRC conversion kit but kinda pricey, more than I wanted to pay just to use the 1911 mags I had lying around. Last I looked the 1911 conversion kit was significantly more expensive than the Glock conversion.  

Not so bad a price:

http://www.gunbroker.com/Auction/ViewItem.aspx?Item=436778658

I got one from the same place great guy and transaction went smooth.

My JR carbine in 9mm has been flawless.  1" groups at 50 yards off the bench with a dot sight.  Mine has been a very reliable arm.  A great PCC, IMO.